Method for driving a field-effect transistor

Abstract

A method for driving a field-effect transistor having a source section, a drain section and a gate section, includes applying a gate voltage to the gate section and causing the formation and/or maintenance of an electrically conductive channel between the source section and the drain section. After the channel has been formed, the gate section is disconnected from a gate voltage supply source which applies the gate voltage to the gate section.

I claim: 
     
       1. In a method for driving a field-effect transistor having a source section, a drain section and a gate section, the improvement which comprises: applying a gate voltage to the gate section and causing at least one of formation and maintenance of an electrically conductive channel between the source section and the drain section;   after the channel has been formed, disconnecting the gate section from a gate voltage supply source applying the gate voltage to the gate section;   after disconnecting the gate section from the gate voltage supply source, changing a source voltage value applied to the source section; and   keeping the gate potential essentially unchanged during the disconnection of the gate section from the gate voltage supply source.   
     
     
       2. The method according to claim 1, which comprises disconnecting the gate section from the gate voltage supply source with a switching device interrupting an electrical connection between the gate section and the gate voltage supply source. 
     
     
       3. The method according to claim 1, which comprises causing the source voltage and a drain voltage to assume values which cause at least one of the formation and maintenance of the electrically conductive channel by interaction with the gate voltage, until the disconnection of the gate section from the gate voltage supply source. 
     
     
       4. The method according to claim 1, which comprises after the disconnection of the gate section from the gate voltage supply source, causing a source voltage to assume values desired to pass through to the drain section. 
     
     
       5. In a method for driving a field-effect transistor having a source section, a drain section and a gate section, the improvement which comprises: applying a gate voltage to the gate section and causing at least one of formation and maintenance of an electrically conductive channel between the source section and the drain section;   after the channel has been formed, disconnecting the gate section from a gate voltage supply source applying the gate voltage to the gate section;   after disconnecting the gate section from the gate voltage supply source, changing a source voltage value applied to the source section; and   placing the gate section in an essentially floating state after the disconnection of the gate section from the gate voltage supply source.   
     
     
       6. The method according to claim 5, which comprises disconnecting the gate section from the gate voltage supply source with a switching device interrupting an electrical connection between the gate section and the gate voltage supply source. 
     
     
       7. The method according to claim 5, which comprises causing the source voltage and a drain voltage to assume values which cause at least one of the formation and maintenance of the electrically conductive channel by interaction with the gate voltage, until the disconnection of the gate section from the gate voltage supply source. 
     
     
       8. The method according to claim 5, which comprises after the disconnection of the gate section from the gate voltage supply source, causing a source voltage to assume values desired to pass through to the drain section. 
     
     
       9. In a method for driving a field-effect transistor having a source section, a drain section and a gate section, the improvement which comprises: applying a gate voltage to the gate section and causing at least one of formation and maintenance of an electrically conductive channel between the source section and the drain section;   after the channel has been formed, disconnecting the gate section from a gate voltage supply source applying the gate voltage to the gate section;   after disconnecting the gate section from the gate voltage supply source, changing a source voltage value applied to the source section;   after disconnecting the gate section from the gate voltage supply source, causing a source voltage to assume values desired to pass through to the drain section, and   also causing the source voltage to simultaneously assume values which would prevent the formation of the channel or would cause it to break down if provided before the disconnection of the gate section from the gate voltage supply source.   
     
     
       10. The method according to claim 9, which comprises increasing the source voltage in steps. 
     
     
       11. The method according to claim 9, which comprises continuously increasing the source voltage.